ABSTRACT
Life within the gravitational envelope of the planet exposes us all to an acceleration directed towards the center of the Earth which has a magnitude of 32 ft/s2 (9.81 m/s2). This gravitational pull, when acting on a mass, gives rise to the force we know as weight.1 All life forms have evolved to operate in this ‘1 G’ environment. However, modern means of transport can expose us to much greater accelerations which may have either physiological or pathological effects, depending on the duration and magnitude of the acceleration, its direction, and rate of application. Short duration accelerations (less than one second duration) may result in injury or death. Examples include forces experienced during crashes or ditching and, for the military pilot, operation of ejection seats, carrier deck catapults, and the opening shock of parachutes.
